<form id="update_score_form" name="update_score_form">
    <fieldset><legend contenteditable="false">修改学生成绩</legend>
        <label contenteditable="false">课程名</label>
        <select name="course_name" id="course_name" onchange="updateScoreStudentSelect()">
        </select><br>
        <label contenteditable="false">学生姓名</label>
        <select name="student_name" id="student_name" onchange="updateScoreStudentScore()">
        </select><br>
        <label contenteditable="false">平时表现</label>
        <input placeholder="平时成绩" type="text" id="performance" name="performance"><br>
        <label contenteditable="false">半期考试</label>
        <input placeholder="半期成绩" type="text" id="midterm" name="midterm"><br>
        <label contenteditable="false">期末考试</label>
        <input placeholder="期末成绩" type="text" id="finals" name="finals"><br>
        <label contenteditable="false">总评</label>
        <input placeholder="总评" type="text" id="overall" name="overall"><br>
        <button class="btn" onclick="updateStudentScore()" contenteditable="false" type="button">提交</button></fieldset>
</form>